Mechanical equipment or the like that is used in a factory has been provided with a signal display lamp. The signal display lamp is a light emitting device that emits a light emission signal to impart a state of the mechanical equipment or the like to its surroundings. The signal display lamp has, for example, a light source and a lens component that guides light from the light source to its surroundings (see Patent Literatures 1 and 2, for example).
The lens component of the signal display lamp of Patent Literature 1 assumes a substantially cylindrical external shape, and has many plate-shaped light guides that are radially disposed. A substrate is attached to an end in the axial direction of the lens component, and a light emitting diode (LED) serving as a light source is mounted on the substrate. Light of the LED is emitted to its surroundings through the lens component.
The lens component of the signal display lamp of Patent Literature 2 assumes a substantially circular-tube shape. A substrate is longitudinally disposed at a central hole of the lens component, and LEDs serving as light sources are mounted on both sides of the substrate.